CORS Error using previewer (Web App)

page.Page27:1 Access to fetch at from origin ‘’ has been blocked by CORS policy: Response to preflight request doesn’t pass access control check: No ‘Access-Control-Allow-Origin’ header is present on the requested resource. If an opaque response serves your needs, set the request’s mode to ‘no-cors’ to fetch the resource with CORS disabled.

I want to link my app with apps script using web app. Please help me solve this CORS


First check that it’s an actual CORS problem and not some other error that is displayed as CORS error by checking in mobile preview if it also fails. If it works on mobile, it’s a CORS error. If it does not work on mobile, it’s a misconfiguration. You can use the web developer console for the error or use something like cURL or Postman to find out the correct configuration for the API.

If it is a CORS error however, it has to be solved from the server/backend side, as we have no way to affect it. If you can not edit the CORS policy, another way to solve this is to set up a proxy for the API.

Hi @Mevi,

It is working on apps. The error happened when I use all web version including apple and android.

I do not know how to solve this CORS issue, Appgyver-Google appscript. The same api works fine if I use Xano-Google appscript.

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Hi! Yes, all web versions would have the same problem. However, the mobile preview app should not have the same problem, if it’s a CORS issue.

If it is a CORS issue, I can’t help you. If it is not a CORS issue, there is some misconfiguration in your API, and you can use the debugger or the developer console (e.g. Chrome’s developer console on the web preview) to find out more about the error.